1. Field of the Invention
The invention is directed to an improved valve for controlling fluids, and more particularly to a fuel injection valve for an internal combustion engine.
2. Description of the Prior Art
One valve of the type with which this invention is concerned is known in the industry and serves in particular as a control module for a fuel injection valve, in particular a common rail injector, of a motor vehicle. This known valve of has a piezoelectric actuator for actuation. A deflection of the piezoelectric actuator is transmitted to a valve closing member upon actuation of the valve, via a hydraulic chamber that acts as a hydraulic booster or coupling and tolerance compensation element. The hydraulic chamber acting as a hydraulic coupler is disposed between an adjusting piston that is connected to the piezoelectric actuator and an actuating piston that is connected to the valve closing member. The diameter of the adjusting piston is greater than that of the actuating piston, so that the actuating piston executes a stroke that is lengthened by the boosting ratio of the piston diameters, when the adjusting piston undergoes a certain deflection by means of the piezoelectric actuator.
The hydraulic chamber is designed such that leaks that occur during operation can be compensated for by refilling. To this end, a fluid pressure, or so-called system pressure, acts on the hydraulic chamber in a system region or system chamber of the valve, for instance via leakage gaps embodied at the circumference of the pistons.
The system region is acted upon by the fluid pressure in such a way that upon an actuation of the valve, the valve closing member is moved into an opening position, and fluid can flow into the system region. The fluid quantity flowing into the system region is the so-called diversion quantity, which is then removed from the system region via a so-called diversion conduit.
In one known valve, the system pressure prevailing in the system region, which is approximately 30 bar, is dammed up by means of a check valve disposed in the diversion conduit, so that the pressure prevailing in the system region is high enough to assure refilling of the hydraulic chamber.
When this valve is used in a fuel injection valve of a motor vehicle, such as a common rail injector, in which a pressure of about 1.5 kbar prevails upstream of the valve closing member, the diversion quantity flows at a high pressure into the system region, so that in the system region pressure spikes occur that may possibly impair the functioning of the actuator module, which is likewise exposed to the system pressure. Moreover, initial filling of the hydraulic coupler at the factory is necessary.